Add RxNetty support

This commit adds RxNetty integration that includes RxNetty-based
implementations of ServerHttpRequest and ServerHttpResponse as well as
an adapter from the RxNetty RequestHandler to the HttpHandler contracts.

Only byte[] is supported at the moment for reading and writing with a
corresponding copy to and from Netty ByteBuf.

spring-web-reactive/src/test/java/org/springframework/reactive/web/rxnetty/HttpHandlerRxNettyIntegrationTests.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2002-2015 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.reactive.web.rxnetty;
+
+import io.netty.buffer.ByteBuf;
+import io.reactivex.netty.protocol.http.server.HttpServer;
+import org.junit.AfterClass;
+import org.junit.BeforeClass;
+
+import org.springframework.reactive.web.EchoHandler;
+import org.springframework.reactive.web.AbstractHttpHandlerIntegrationTestCase;
+
+/**
+ * @author Rossen Stoyanchev
+ */
+public class HttpHandlerRxNettyIntegrationTests extends AbstractHttpHandlerIntegrationTestCase {
+
+	private static HttpServer<ByteBuf, ByteBuf> httpServer;
+
+
+	@BeforeClass
+	public static void startServer() throws Exception {
+		RequestHandlerAdapter requestHandler = new RequestHandlerAdapter(new EchoHandler());
+		httpServer = HttpServer.newServer(port);
+		httpServer.start(requestHandler::handle);
+	}
+
+	@AfterClass
+	public static void stopServer() throws Exception {
+		httpServer.shutdown();
+	}
+
+}